#weekendusers From Antarctica to the beamline

A Belgian team is trying to find out about the origin of the Solar System by studying micrometeorites from Antarctica on the Dutch-Belgian beamline (DUBBLE).

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Sør Rondane Mountains, Antarctica, 2013. Steven Goderis, from the Analytical Environmental and Geochemistry (AMGC) research group in the Vrije Universiteit Brussel (Belgium), is part of a Japanese-Belgian expedition looking for meteorites preserved in the cold and dry environment of the South Pole. And they hit the jackpot: they found 635 fragments of micrometeorites. After coming back with the precious load, similar meteorite recovery expeditions and field campaigns focusing on micrometeorites continued in the following years, all equally successful. To date, they have found hundreds of pieces of meteorites and thousands of pieces of micrometeorites.

While part of the team is at DUBBLE, the rest are in Antarctica looking for new samples. Credits: C. Argoud and S. Goderis.

So what is the point of micrometeorites? Of all the material reaching Earth from space only a small part will survive the heating and shock experienced upon entry in the atmosphere. The large majority of this material, the micrometeorites, will rain on Earth as extraterrestrial particles of less than 2mm in size. Although meteorites in general provide us with essential information on the origin and evolution of the planets and the Solar System, micrometeorites, mostly originating from the most primitive objects still remaining in the Solar System, raise an even higher scientific interest. “Any information we can get from micrometeorites will complement the knowledge we have of meteorites, so it is really important to study them. We have a wide array of samples so that we can get the best possible picture of these materials”, explains Bastien Soens, who is doing his PhD on this subject.

The team on the beamline. From left to right: Niels de Winter, Bastien Soens, Dip Banerjee, Stephen Bauers and Niels Collyns. Credits: C. Argoud.

Steven Goderis, together with colleagues at the Vrije Universiteit Brussel and Ghent University (Belgium), has studied the samples using different techniques. This weekend, while he is looking for new samples in Antarctica, his team is at BM26A, the Dutch-Belgian BeamLine (DUBBLE) at ESRF trying to elucidate the chemical composition of the micrometeorites. "We are using X-ray fluorescence to quantify the presence of elements like zinc or copper, and X-ray absorption spectroscopy to define the chemical state of the iron present in the samples”, explains Stephen Bauters, part of the team. “The DUBBLE beamline is ideal for non-destructive 2D/3D micro analysis using confocal X-ray fluorescence and absorption spectroscopy, as we could not characterise the samples using even the most sensitive, state-of-the-art laboratory X-ray microbeam instrument”, says Bauters.

Bastien Soens checks the pieces of meteorites. On the right, a piece of meteorite in Antarctica. Credits: M. Capellas Espuny and S. Goderis.

When the results will be analysed, the scientists expect to obtain a better understanding of the physico-chemical processes affecting cosmic dust particles during atmospheric entry. Ultimately, though, as Soens explains, “we want to determine where these samples came from in the Solar System, to better understand how the Solar System formed”.

Text by Montserrat Capellas Espuny

Top image: The MICROMETA expedition cruising in the Antarctica looking for meteorites. Credits: S. Goderis.